Refrigerant composition containing PTFE

ABSTRACT

A refrigerant composition is disclosed which includes a lubricant. The refrigerant composition includes formulations for use in automotive, residential or building air conditioning units. The refrigerant composition includes 90% to 99.5% by weight of a refrigerant, and 10% to 0.5% by weight of polytetrafluoroethylene particles. The polytetrafluoroethylene particles range in size from 0.2 μm to 8.0 μm.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a refrigerant composition, whichincludes a lubricant for use in a refrigeration system.

2. Description of Related Art

Refrigerant fluids generally have powerful degreasing properties.Therefore, adequately lubricating the piston and cylinder walls and thebearings of the compressor used in cooling systems has heretoforepresented a problem. In addition, there is the problem of adequatelylubricating the moving parts of valves used in the cooling system. Inpast practice, an excess of lubricating oil was provided within thecooling system to provide some lubrication of the moving parts.

Examples of the application of PTFE particles can be seen among thereferences cited below. The McCoy et al. Patent shows the use of PTFEparticles in a lubricant composition intended primarily as an enginelubricant. The Holzknecht patent relates to a leak sealer forrefrigeration systems. The leak sealer of Holzknecht relies on theagglomeration of PTFE particles to plug leaks, and therefore theparticle sizes in the composition of Holzknecht are quite large.

None of the references cited below provide for a refrigerantcomposition, which allows for the enhanced lubrication of parts within acooling system. Therefore, the need persists in the art for arefrigerant composition, which provides for enhanced lubrication of theparts of a cooling system.

U.S. Pat. No. 5,792,728, issued to Lin-sen Yuan et al. on Aug. 11, 1998is directed to a cutting fluid composition for use in machiningoperations. The cutting fluid composition includes molybdenum disulfidepowder, soap flakes, a liquid PTFE suspension and water. The liquid PTFEsuspension used by Yuan et al. is composed of PTFE, water and asurfactant. Yuan et al. do not disclose the range of PTFE particle sizesused in their composition.

U.S. Pat. No. 5,744.539 issued to Frederic C. McCoy et al on Apr. 28,1998 is directed to lubricant compositions having PTFE (a.k.a. TEFLON®)particles with an average size ranging from 4 to 6 microns dispersedtherein. The compositions of McCoy et al also include dispersing agentswhich help keep the TEFLON® particles from separating from thelubricating oil.

U.S. Pat. No. 5,650,563 issued to B. William Cooper et al on Jul. 22,1997 and U.S. Pat. No. 5,440,919 issued to B. William Cooper on Aug. 15,1995 are directed to methods of introducing a leak detection dye into arefrigeration apparatus. The methods involve the placement of an inertdye impregnated carrier or the placement of a solid pellet of a dye inthe desiccant bag of a dehydrator used in the refrigeration apparatus.

U.S. Pat. No. 5,378,123 issued to Carmelo J. Scuderi et al on Jan. 3,1995 is directed to an apparatus for recovering refrigerant from arefrigeration system. The apparatus includes a liquid trap, whichseparates the gaseous refrigerant from the liquid refrigerant. Theliquid refrigerant from the liquid trap goes to a liquid receiver, whilethe gaseous refrigerant is directed to a condenser where it is liquefiedand then directed to the same liquid receiver.

U.S. Pat. No. 4,487,707 issued to Robert H. Holzknecht on Dec. 11, 1984is directed to a leak sealing composition for refrigeration systems. Thecomposition of Holzknecht includes graphite or TEFLON® particles,ranging in size from 20 microns to 65 mesh, suspended in refrigerationoil.

None of the above inventions and patents taken either singly or incombination, is seen to describe the instant invention as claimed.

SUMMARY OF THE INVENTION

The present invention is directed to a refrigerant composition, whichincludes a lubricant. The refrigerant composition of the presentinvention includes formulations for use in both automotive andresidential or building air conditioning units. The refrigerantcomposition of the present invention includes 90% to 99.5% by weight ofa refrigerant, and 10% to 0.5% by weight of polytetrafluoroethyleneparticles. The polytetrafluoroethylene particles used in the presentinvention range in size form 0.2 μm to 8.0 μm.

Accordingly, it is a principle object of the invention to provide arefrigerant composition, which allows the adequate lubrication of movingparts within a cooling system.

It is another object of the invention to provide a refrigerantcomposition, which includes solid lubricating particles, which will notbe dissolved by the refrigerant component of the composition.

It is a further object of the invention to provide a refrigerantcomposition, which includes PTFE particles.

Still another object of the invention is to provide a refrigerantcomposition which includes PTFE particles that are small enough topenetrate the interstices between the parts of a cooling system.

It is an object of the invention to provide improved elements andarrangements thereof in an apparatus for the purposes described which isinexpensive, dependable and fully effective in accomplishing itsintended purposes.

These and other objects of the present invention will become readilyapparent upon further review of the following specification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to a refrigerant composition for usein a refrigeration system. In particular, the compositions of thepresent invention are suited for use in automotive and building coolingsystems or air conditioning units. The refrigerant compositions of thepresent invention include 90.0% to 99.5% by weight of a refrigerant, and10.0% to 0.5% by weight of polytetrafluoroethylene (PTFE) particles.Refrigerant fluids generally have powerful degreasing properties.Therefore, adequately lubricating the piston, cylinder walls and thebearings of the compressor used in the cooling system has alwayspresented a problem. In addition, there is the problem of adequatelylubricating the moving parts of valves used in the cooling system. Ithas been found that including very fine PTFE particles in therefrigerant fluid, greatly enhances the lubrication of moving partswithin the cooling system.

The preferred refrigerants or refrigerant fluids for use in the presentinvention are tetrafluoroethane, chlorodifluoromethane, andchlorotrifluoromethane. An example of a suitable tetrafluoroethane is1,1,1,2-tetrafluoroethane marketed by Dupont under the trade name SUVA®134a. Chlorodifluoromethane and chlorotrifluoromethane are marketed byDupont under the trade names FREON® 22 and FREON® 13, respectively.

The PTFE particles used in the present invention are marketed by Dupontunder the designation ZONYL® MP 1100 fluoroadditive. ZONYL® MP 1100 is awhite free-flowing powder made of PTFE particles. The primary particlesize of the PTFE particles constituting the ZONYL® MP 1100 is 0.2 μmwhich agglomerate to give an average particle size of 150 μm in thepowder as supplied by the manufacturer. When the powder is suspended inrefrigerant fluids and subjected to agitation, the agglomerates breakdown and the particle size most closely approaches the primary particlesize of 0.2 μm. The compositions of the present invention are preparedby mixing the ingredients and agitating, an operation, which subjectsthe agglomerates to shearing forces. Preferably the mixing should becarried out so as to subject the agglomerates to at least moderateagitation. Moderate agitation forces will yield particle sizes which onaverage range from 0.2 μm to 8.0 μm. Most commonly, moderate agitationyields a particle size distribution such that about 90.0% by volume ofthe polytetrafluoroethylene particles are smaller that about 8.0 μm insize. Even more preferably, the mixing conditions should be selectedsuch that the agglomerates are subjected to high agitating forces suchthat the agglomerates break down to yield particles whose average sizeis in the range of 0.5 μm to 0.75 μm.

An example of a suitable refrigerant composition according to thepresent invention for automotive air conditioning systems is obtained bymixing, about 99.0% by weight of refrigerant, and about 1.0% by weightof the PTFE particles, under conditions of moderate to high agitation.An example of a suitable refrigerant composition according to thepresent invention for building cooling or air conditioning systems isobtained by mixing about, 98.0% by weight of refrigerant, and about 2.0%by weight of the PTFE particles under conditions of moderate to highagitation.

The refrigerant composition was tested on a home air conditioningsystem. With the air conditioning system charged with the refrigerantformulation described above for building air conditioning systems, asopposed to the standard refrigerant composition for the particular airconditioning system, the current drawn by the air conditioner compressordropped by 10% for the same cooling effect, as indicated by an ampmeter. Thus, the use of the refrigerant compositions of the presentinvention in cooling systems can result in substantial energy savings.

It is to be understood that the present invention is not limited to theembodiments described above, but encompasses any and all embodimentswithin the scope of the following claims.

I claim:
 1. A refrigerant composition comprising: 90.0% to 99.5% byweight of a refrigerant; 10% to 0.5% by weight ofpolytetrafluoroethylene particles.
 2. The refrigerant compositionaccording to claim 1, wherein said refrigerant is present in the amountof about 99.0% by weight, and said polytetrafluoroethylene particles arepresent in the amount of about 1.0% by weight.
 3. The refrigerantcomposition according to claim 2, wherein said refrigerant is selectedfrom the group consisting of 1,1,1,2-tetrafluoroethane,chlorodifluoromethane, and chlorotrifluoromethane.
 4. The refrigerantcomposition according to claim 2, wherein said polytetrafluoroethyleneparticles range in average size from 0.2 μm to 8.0 μm.
 5. Therefrigerant composition according to claim 2, wherein saidpolytetrafluoroethylene particles have a size distribution such thatabout 99.0% by volume of said polytetrafluoroethylene particles aresmaller than about 8.0 μm in size.
 6. The refrigerant compositionaccording to claim 1, wherein said, refrigerant is present in the amountof about 98.0% by weight, and said polytetrafluoroethylene particles arepresent in the amount of about 2.0% by weight.
 7. The refrigerantcomposition according to claim 6, wherein said refrigerant is selectedfrom the group consisting of 1,1,1,2-tetrafluoroethane,chlorodifluoromethane, and chlorotrifluoromethane.
 8. The refrigerantcomposition according to claim 5, wherein said polytetrafluoroethyleneparticles range in average size from 0.2 μm to 8.0 82 m.
 9. Therefrigerant composition according to claim 6, wherein saidpolytetrafluoroethylene particles have a size distribution such thatabout 98.0% by volume of said polytetrafluoroethylene particles aresmaller than about 8.0 μm in size.
 10. The refrigerant compositionaccording to claim 1, wherein said polytetrafluoroethylene particlesrange in average size from 0.2 μm to 8.0 μm.
 11. The refrigerantcomposition according to claim 1, wherein said polytetrafluoroethyleneparticles have a size distribution such that about 99.0% by volume ofsaid polytetrafluoroethylene particles are smaller than about 8.0 μm insize.
 12. The refrigerant composition according to claim 1, wherein saidpolytetrafluoroethylene particles range in average size from 0.5 μm to0.75 μm.